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    <script>
      // 目标：** 编写一个函数，接受一个数组作为参数，并返回数组中所有奇数的平均值（如果没有奇数则返回0）

      function fn(a) {
        let sum = 0
        let count = 0
        for (let i = 0; i < a.length; i++) {
          // console.log(arr[i])

          if (arr[i] % 2 !== 0) {
            sum += a[i]
            count++
          }
        }
        if (count === 0) {
          return 0
        } else {
          return sum / count
        }
      }

      let arr = [1, 2, 3, 4]
      let res = fn(arr)
      console.log(res)

      // function fn(a) {
      //   let newArr = []
      //   for (let i = 0; i < a.length; i) {
      //     if (a[i] % 2 !== 0) {
      //       newArr.push(a[i])
      //     }
      //     let sum = 0
      //     for (let j = 0; j < newArr.length; j++) {
      //       sum += newArr[j]
      //     }
      //     return sum / newArr.length
      //   }
      // }
      // let arr = [3, 4, 5, 6]
      // let res = fn(arr)
      // console.log(res)
    </script>
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